Will Internet Access Via Drones Ever Fly?

Google (Project Loon) via YouTube

As the World Economic Forum highlighted in a report earlier this year, while our increasingly hyperconnected world brings many benefits, it also exacerbates inequalities for those large portions of the global population that have limited or no internet access.

Recently, though, two initiatives — Google’s Project Loon and Mark Zuckerberg’s internet.org — have drawn widespread attention to the challenge of using alternative delivery platforms to bring low cost broadband access to unserved or underserved parts of the world.

Project Loon plans to bring internet access to remote locations via a network of high-altitude balloons. As Google describes it, “People can connect to the balloon network using a special Internet antenna attached to their building. The signal bounces from this antenna up to the balloon network, and then down to the global Internet on Earth.

Internet.org is taking a similar approach, except instead of balloons, it envisions using drones as the delivery platform.

The benefits of an all-wireless network in the sky are clear. Such a network would be far less expensive, far less disruptive and take far less time to build than implementing a wired / land based infrastructure over very large swaths of the earth where no communications infrastructure currently exists. But are such networks just hype or could they really work?

How Viable Are Airborne Networks?

While such a network may seem fantastical, the concept of an airborne-based network isn’t all that far-fetched.

Several years ago, our engineering team, consisting of leading aerospace engineers, optics experts and computer scientists, successfully developed the first ultra-high bandwidth wireless network in the sky under contract with the U.S. military. The technology was capable of sending large amounts of data — from 10 Gbps up to 80 Gbps — between moving aircraft or between aircraft and ground stations up to 200 kilometers away. This was something that had never been achieved before.

Yet, while Project Loon’s balloons and internet.org’s drones won’t need networking equipment nearly as powerful as what we built for the military, they will still face significant challenges creating networks that float above the clouds and that are suitable for providing internet access to remote populations.

Delivering Adequate Bandwidth Over Long Distances

One of the key challenges Google Loon and internet.org will face with their airborne networks will be choosing the best wireless technology to connect the drones or balloons to the internet with enough capacity to support multiple users.

All the data traffic from multiple users on the ground will get aggregated at the airborne platform. From there, the data may get sent to a series of other balloons or drones (to cover longer distances), and then eventually to a link on the earth’s surface that connects to the internet. Wireless technologies available today suitable for this are limited, and primarily include microwave, millimeter wave and free space optics.

Each of these has limitations: microwave has relatively low capacity, while millimeter wave and free space optics (FSO) are affected by weather (millimeter wave doesn’t work well in rain, while FSO performance is affected by fog).

In our work with the military, we used an advanced version of FSO technology enhanced with Curvature Adaptive Optics, a technology originally developed for deep space imaging. The adaptive optics used in these systems were small lens-shaped mirrors that warped and changed shape thousands of times per second to compensate for atmospheric scintillation. Atmospheric scintillation is phenomenon that makes stars or city lights appear to flicker, and it can also introduce errors when transferring data.

While our adaptive optics innovations allowed us to send massive amounts of data over a very narrow beam of light (about four inches in diameter) hundreds of kilometers, it didn’t completely solve one issue all FSO technologies suffer from — reduced performance in fog.

Maintaining a Reliable Connection

Keeping data flowing across a wireless communication link through a range of weather conditions without suffering reduced performance or outright loss of signal will be another challenge. The telecom industry has tried a range of different approaches to improve the uptime of prevailing wireless technologies, but these solutions have mostly resulted in small, incremental improvements.

What has worked is combining two diverse wireless technologies (such optical and millimeter wave signals) that can compensate for each other’s shortcomings without interfering with each other’s signal. In this setup, both signals need to be treated as equals, versus the alternative of treating one signal as a primary and the other as a backup, thus allowing for the output data streams to be combined to yield the strongest possible received signal. With this approach, the link can deliver fiber-like performance in terms of speed and reliability, even over fairly long distances.

Moving Targets

The other major challenge with airborne platforms is movement — even a relatively stationary balloon will have some amount of movement.

This may not sound like a big deal, but it can be frustratingly complicated to overcome from a technological standpoint. It was one of the most complex aspects of our work with the military.

Many of today’s high-capacity wireless technologies transmit data over relatively narrow beams. To work with airborne platforms, the system must be able to quickly establish and maintain a constant connection between each transceiver on either side of the link. The longer the link, the harder this is to do.

Highly specialized tracking hardware and software algorithms are needed to acquire the signal and maintain link alignment through rapid coarse, fine and ultra-fine link adjustments. Otherwise, if perfect alignment isn’t maintained, the signal will be broken.

Both Project Loon and internet.org will likely need links of at least several miles. To give you a sense of how narrow the margin of error is, if two wireless transceivers are placed five miles apart and one is off track by a mere one degree, the signal would miss its target by almost 500 feet. The longer the link, the narrower this margin becomes.

Will It Ever Happen?

The vision that Google Loon and internet.org have laid out is admirable and the potential benefits of such networks for underserved segments of the population and society overall would be substantial. The wireless systems used to transmit data will need to be shrunk down in both size and cost, and although there are still many technical hurdles to address, from a technology standpoint such networks are entirely possible today. However, it remains to be seen if these organizations will be able to break through political and social barriers within specific regions. In the end, those forces may prove much harder to counter and will take sheer, sustained determination to resolve.